def FindNum(ls:list=[1,5,2,7,4,9],Num=11):
    nlen=len(ls)
    ret=[]
    for i in range(0,nlen):
        for j in range(i+1,nlen):
            if ls[i] + ls[j] == Num:
                ret.append((ls[i],ls[j]))
    
    return ret


print(FindNum())

# 实现的不错，可以尝试一下使用in操作符来实现